wiedld commented on code in PR #7614:
URL: https://github.com/apache/arrow-datafusion/pull/7614#discussion_r1334862713
##########
datafusion/expr/src/type_coercion/functions.rs:
##########
@@ -136,62 +137,100 @@ fn maybe_data_types(
///
/// See the module level documentation for more detail on coercion.
pub fn can_coerce_from(type_into: &DataType, type_from: &DataType) -> bool {
- use self::DataType::*;
-
if type_into == type_from {
return true;
}
- // Null can convert to most of types
+ if let Some(coerced) = coerced_from(type_into, type_from) {
+ return coerced == type_into;
+ }
+ false
+}
+
+fn coerced_from<'a>(
+ type_into: &'a DataType,
+ type_from: &'a DataType,
+) -> Option<&'a DataType> {
+ use self::DataType::*;
+
match type_into {
- Int8 => matches!(type_from, Null | Int8),
- Int16 => matches!(type_from, Null | Int8 | Int16 | UInt8),
- Int32 => matches!(type_from, Null | Int8 | Int16 | Int32 | UInt8 |
UInt16),
- Int64 => matches!(
- type_from,
- Null | Int8 | Int16 | Int32 | Int64 | UInt8 | UInt16 | UInt32
- ),
- UInt8 => matches!(type_from, Null | UInt8),
- UInt16 => matches!(type_from, Null | UInt8 | UInt16),
- UInt32 => matches!(type_from, Null | UInt8 | UInt16 | UInt32),
- UInt64 => matches!(type_from, Null | UInt8 | UInt16 | UInt32 | UInt64),
- Float32 => matches!(
- type_from,
- Null | Int8
- | Int16
- | Int32
- | Int64
- | UInt8
- | UInt16
- | UInt32
- | UInt64
- | Float32
- ),
- Float64 => matches!(
- type_from,
- Null | Int8
- | Int16
- | Int32
- | Int64
- | UInt8
- | UInt16
- | UInt32
- | UInt64
- | Float32
- | Float64
- | Decimal128(_, _)
- ),
- Timestamp(TimeUnit::Nanosecond, _) => {
- matches!(
+ // coerced into type_into
+ Int8 if matches!(type_from, Null | Int8) => Some(type_into),
+ Int16 if matches!(type_from, Null | Int8 | Int16 | UInt8) =>
Some(type_into),
+ Int32 if matches!(type_from, Null | Int8 | Int16 | Int32 | UInt8 |
UInt16) => {
+ Some(type_into)
+ }
+ Int64
+ if matches!(
+ type_from,
+ Null | Int8 | Int16 | Int32 | Int64 | UInt8 | UInt16 | UInt32
+ ) =>
+ {
+ Some(type_into)
+ }
+ UInt8 if matches!(type_from, Null | UInt8) => Some(type_into),
+ UInt16 if matches!(type_from, Null | UInt8 | UInt16) =>
Some(type_into),
+ UInt32 if matches!(type_from, Null | UInt8 | UInt16 | UInt32) =>
Some(type_into),
+ UInt64 if matches!(type_from, Null | UInt8 | UInt16 | UInt32 | UInt64)
=> {
+ Some(type_into)
+ }
+ Float32
+ if matches!(
type_from,
- Null | Timestamp(_, _) | Date32 | Utf8 | LargeUtf8
- )
+ Null | Int8
+ | Int16
+ | Int32
+ | Int64
+ | UInt8
+ | UInt16
+ | UInt32
+ | UInt64
+ | Float32
+ ) =>
+ {
+ Some(type_into)
}
- Interval(_) => {
- matches!(type_from, Utf8 | LargeUtf8)
+ Float64
+ if matches!(
+ type_from,
+ Null | Int8
+ | Int16
+ | Int32
+ | Int64
+ | UInt8
+ | UInt16
+ | UInt32
+ | UInt64
+ | Float32
+ | Float64
+ | Decimal128(_, _)
+ ) =>
+ {
+ Some(type_into)
+ }
+ Timestamp(TimeUnit::Nanosecond, None)
+ if matches!(
+ type_from,
+ Null | Timestamp(_, None) | Date32 | Utf8 | LargeUtf8
+ ) =>
+ {
+ Some(type_into)
}
- Utf8 | LargeUtf8 => true,
- Null => can_cast_types(type_from, type_into),
- _ => false,
+ Interval(_) if matches!(type_from, Utf8 | LargeUtf8) =>
Some(type_into),
+ Utf8 | LargeUtf8 => Some(type_into),
+ Null if can_cast_types(type_from, type_into) => Some(type_into),
+
+ // timestamp coercions, with timezone, accept the type_from timezone
if valid
+ Timestamp(TimeUnit::Nanosecond, Some(_))
+ if matches!(
+ type_from,
+ Timestamp(TimeUnit::Nanosecond, Some(from_tz)) if
arrow_array::timezone::Tz::from_str(from_tz).is_ok()
Review Comment:
Ah, yes! We would have had a parser error if the tz string was invalid.
Excellent point.
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